Pressure still for cracking oils



Jan. 6, 1931. D. A. YOUNG PRESSURE STILL FOR CRACKING OILS Filed July15, 1927 2 Sheets-Sheet 1 pa MM 4. young Jan. 6, 1931. D. A; YOUNG 8,006

PRESSURE STILL FCR CRACKING OILS Filed July 15 1927 2 Sheets-Sheet 2INVENTOR David A. young -20 the pressure still bymeans Patented Jan. 6,1931 UNITED e was mm; A. YOUNG, or cnn's'rnn, DELAWARE, Assrenon 1T0'smoLAm nnrmmecomrANY, on nEw YORK, n; "1., A CORPORATION OF'MAINE-rnnssunn s'rILL FOR cnAoxrNG one i Application med July 15, 1927.Ser-ia1No. 205,967.

In, the distillation of hydrocarbon oils under pressure, for :theproduction,bycracking, of lighter and lowerboilingioilsfrom heavier andhigher boiling oils, it has become 5 common practice to prolong theperiod of operation by discharging, from the pressure still in which theoperation is carried out, a part of the oil remainingunvaporizedin thestill. One such particularly advantageous method of operationlsdescribed in Letters Patent No.,.1,598,136 issued to the SinclairRefining- Company, August 31, 1926; another such particularlyadvantageous method of operation isdescribed in Letters Patent No.1,634,666 issued to the SinclairBefining Company on an application filedApril 8, 1924:, Serial No. 704,926. Hitherto, in such operations, ithasbeen customary to regulate the discharge of-unvaporizedoil fromranged in the discharge line externally of the still- I This inventionrelatesto an improved ar rangement of the regulating valve in thedischarge line for carrying out this'typepf operation in pressurecracking stills. The m vention has several important-advantages; itimproves the regularity'of operation of I such discharge lines and italsoassists in keeping such discharge lines cleanover practicallyindefinite periods oftime. L Where the regulating valve is arranged inthe discharge line externally of the still, particularly. where thedischarge line extends into the still for any substantial distance, thedischarge line tends to become'plugged or stopped, more or lessfrequently, between the regulating valve andthe inner end of the lineopening into the still. lhe unvaporized oil in a pressure cracking stillusually contains a fairly large proportion of pitchy or asphalticconstituents and frequentlycontains a substantialamount of suspendedsolid or semi-solid carbonaceous material. jWithi'n the confines of arelativelywsmall pipe, par; ticularly where the velocity islow, theseconstituents tend to form deposits which build up,plugging or stoppingthe line, Likewise, in some cases, cracking of the 011 may continue asit passes through the'disfchargelme of a valve ar andmay result in theformation of coky or carbonaceous deposlts 1n the line as a consequence.

According to the present invention, the

regulating valve'for controlling the discharge of unvaporized oil fromthe still'is arranged within the still and at'the extreme inner end. ofthedischarge line. By this means, the reduction in pressure which takesplace at this regulating valve in operation is madeefiective 'justassoon as the oil enters the discharge line" so that the increase invelocity due to'vaporization resulting from thisreduction in pressure isalso made effective throughout the discharge line. This lncrease invelocity inhibits any tendency toward the formation ofcarbonaceous.depositsin the discharge line and, when made effectivethroughout the discharge line in ac'-' cordance with the presentinvention, keeps the discharge line clean throughout its lengthpractically indefinitely. Further, in ac} cordance withthe presentinvention, the'operating extension for the regulating valveadvantageously is "carried to the outside of the pressure still throughthe dischargeline, eliminating any necessity for astuifing box exposedto the pressure and temperature prevailing in the still proper.

The invention will be further described in ventionally apparatusembodying the inventime In the accompanying drawings v Fig. 1represents, inelevationand partly in section and with parts broken away,a pressure still system embodying the inven-' tion, I

"Fig. 2 is a fragmentary elevation of a modified pressure still system,

Fig. 3"iS an enlarged fragmentary view showing a discharge line andregulating valvearranged in accordance with the invention, i

Fig. 4 is asimilarly enlarged view normal toFig.,3, I

Fig. '5 is a furtherenlarged detail of the regulating valve illustratedin Figs. 1 to A,

Fig. 6 is aview similar, to Fig; 5, showing 6 including a circulatingpump 7 forcirculating oil from the bulk supply drum upwardly through theheatingritubes and back to the bulk supply drum. Vapors from the bulksupply drum 1 escape through vapor line 8to the reflux tower 9 locatedabove the bulk'supply drum and vapors remaining on condensed escape fromthe reflux tower through vapor line ,10 to the condenser .11 arranged todischarge into the receiver 12. The distillate product is dischargedfrom re 7 ceiver 12 through connection 13 and uncona run and for densedvapors and gasesthrough connection 14. The pressurein the system may bemaintained and regulated bymeans of valve 15 in the vapor line betweenthe reflux tower 9 and the condenser 11 or by means of. suitable valvesarranged beyond'the' condenser ll'or' the receiver 12. Raw oilisintroducedinto theupper end of the reflux tower'9 through connection16, and is preheat-ed as itfiows through the reflux tower 9 at the sametime assisting in cooling and condensing the heavier part'of the vaporspassing therethrough. Admixed raw oiland reflux-con densate flow back tothe pressure still from the lower end of the reflux tower 9 throughreturn line.17. A part of the cool raw oil is also supplied throughconnection 18 to assist' in cooling and lubricating the bearings of thecirculating pump 7, being forced into the circulating still chargethrough the pump bearings. Discharge line 19 is provided'for thedischarge, during operation, of "unvaporized pitch-laclen oil or, tarfrom the pressure still. Connection 20 is provided'for initiallychargingthe still at the beginning of pumping out the stillat the end ofa run.

In the modified pressure still system illus-l trated inFig. 2, a bed 21of fullers earth, or similar absorbent material, is arranged in the bulksupply drum 1 on a screen 22 extending entirely across the bulk supplydrum between the circulating connect-ions 4 to the battery of heatingtubes and the circulating connection 6 from the battery of heatingtubes. With this arrangement, the charge of oil circulating in thepressure still is caused to circulate and recirculate through the bed offullers earth, or the like, as it circulates and recirculates throughthe heating tubes.

3 I Otherwise, the arrangement of this still sys tem is in general thesame as that illustrated in Fig. 1. t I i V The present inventionrelates particularly sure still (the extension is designated 19a) andthe regulating valve for controlling the discharge of unvaporized oilfrom the body of oil: inthestilldruhi is located within the drum mistthe inner end of the extension 19a.11;Instead ofpassingdirectly throughthe wall of the drum 1, the operating extension for this valve passestothe outside of the still through the discharge line, as shown in Figs.

'The valve propeig'th'at is the closure means atthe inner end of thedischarge line, may be" of several" diifering forms. The formillustrated in ig. 5'has been found particularly simple and eflective.As shown, it consists'of a conical plug 23 adapted to seat in the endofthe discharge line extension 19a movable toward and away from" this seatby an operating extension 24 carried to the outsideof the pressurestill-through the extension 19a" and through :a stufling box 25 arranged in the' discharge line externally of the still. "The operatingextension 24 may or may not be keyed against rotation and adjustment of.itslyposition is provided by a threaded stem 26, to which it isconnected, passing through a rotatable nut 27 The end of theiextension19a forming a seat for the plu'g' 23 may be reinforced by a ring 28.

"The=closure means, in the form of valve illustrated in Fig. 6 and .7,consists of a plug 29, slidingwithinthe end of the discharge lineextension 19a over a number of ports 30. This :p'lug may be guided bypins 31 moving in slots 32 in the extension 19a. The closure means, inthe'form' of valve illustrated in F 1gs.'8'-and 9, consistsof a plug 33sliding .within'the end of the discharge line extenof the' 'raw oil aswell as on the character of'th'e products desired. For the productionofgasoline or gasoline-containing pressure distillate from gas oil, forexample, pressures in the neighborhood 01'5100 to 300 pounds per squarein'ch ma-y be used and the distillation maybe carried out atcorresponding temperatures. After the still is brought to operatingconditions of temperature and pressure, theintroduction of raw oil isbegun and, in pressure still systems of the type illustrated, theintroduction of raw oil into the upper end of the reflux tower may beregulated to condense and return to the pres sure still those componentsof the vapors heavier than desired as components of the distillateproduct. Likewise, either shortly after the still is brought tooperating conditions of temperature and pressure or some time later,.thedischarge of unvaporized oil through the discharge line 19 is begun. Itwill be understood thatthe lower end of the discharge line extension 19ais arranged somewhat below the normal liquid level in the drum of thepressure still. Where a bed of absorbent material is used,as in theapparatus illustrated in Fig. 2, the lower end of the discharge lineextension 19a is advantageously arranged intermediate the liquid levelin the still and the topof the bed.

Up to the time when the discharge otunvaporized oil through line 19 isbegun, this line 19 is kept closed by means'of the valve at the innerend of the line within the still drum. The block-valve 37 is provided inthe discharge line 19 simply for emergency use. When it is desired tobegin the discharge of unvaporized oil, the valve at the inner end ofthe discharge line extension 19a is gradually opened until the desiredrate of flow is established. Thereafter, the operation, it may be closedor partially closedor further opened as required to maintain or vary therate of discharge of vunvaporized oil from the body of oil in thepressure still.

The reduction in pressure effected by the regulating valve at the innerend of the discharge line, in operation, results in a partialvaporization of lighter components of the discharged oil which in turnincreases the volume of oil and consequently the velocity with which itflows through the discharge line, and, in the apparatus of the presentinvention this increase in velocity is effective throughout thedischarge line, from its extreme inner end, to flow and preventingdeposition which might tend to plug or stop the line.

Some of the advantages of the invention may be realized by arran ing theregulating valve on the inner end oi the discharge line within the stilldrum and carrying the operating extension of the valve to the outside ofthe still through a stuffing box arranged d1- rectly'in the still shell;but the arrangement more particularly described in connectlon with theaccompanying drawings, with the operating extension of the valve carriedto the outside of the still through the discharge line, is particularlyadvantageous.

In the apparatus illustrated, it will be noted that the discharge lineextends into the drum downwardly from above the normal liquid level andopens downwardly into-the point during assist in maintaining body of oilin the still. This arrangement of the discharge line also assists inpreventingstopping'or pluggingdue to deposition of carbonaceous solid orsemi-solid material therein,v for example, as compared to a dischargeline openinginto the bottom of the still drum or openlng upwardlyintothe charge of oil therein. .The present invention is of specialvalue and application in connection with pressure still systems in whichthe discharge line is so arranged as it provides for arrangement oftheregulating valve inthe discharge line at the extreme inner end of thedischarge line even though the discharge line extends inwardly into thestill drum for a substantial distance.

Where the regulating valve has been arranged in the discharge lineexternally of the still drum, particularly where the discharge line hasextended into the still drum for a substantial distance, the relativelyslow velocity of the unvaporized oil passing through the discharge linebefore reaching the regulating valve has tended to cause stopping orplugging of the discharge line at a between the regulating valve and theinterior of the still necessitating, when any such stopping or pluggingoccurred, premature shut down of the pressure still with consequent lossof time in useful production. This invention eliminates premature shutdown of pressure cracking stills due to this cause.

I claim: 1. In a pressure carbon oils havlng a still for crackinghydrodrum adapted to contain a body of oil and a line for dischargingunvaporized oil 'from such body extending a substantial distance intosaid drum, a valve'for, controlling the discharge of oil through saidline located within said drum and at the inner end of said line havingan operating extension to the outside of said drum passing through thewall of said drum withinsaid line.

'2. In a pressure still for cracking hydrocarbon oils the improvementcomprising a drum adapted to contain a body of oil, a line ,fordischarging 'unvaporized oil from such body, from a substantial andbelow the normal liquid level of the body of oil therein to a pointexternal of the pressure still, means for maintaining super-atmosphericpressure on the pressure still including a valve for controlling thedischarge of oil through said line, said valve being located within saiddrum and at the inner end of said line, and an operating extension fromsaid valve to the outside of said druml In testimony whereof, I havesubscribed my name.

DAVID A. YOUNG.

said line being arranged to extend distance within said drum

